When The Count Cannot Be Started Or Cannot Be Performed Normally - Mitsubishi Electric MELSEC iQ-R Series User Manual

When the count cannot be started or cannot be performed
normally
Check item
Check whether the external wiring to the terminal block is normal.
Measures to reduce Check whether a shielded twisted pair cable is used for
noise the pulse input cable.
Check for the intrusion of noise from the grounding part
of the pulse input module.
Check whether measures to reduce noise have been
implemented within the panel and on adjacent devices.
Check whether the distance between high voltage
devices and the pulse input cable is sufficient.
Apply voltage to the pulse input terminal from a stabilized power supply or a
similar device and check whether the CH LED turns on.
Check whether the "Input voltage selection" setting of the module parameter
matches the actual input pulse voltage.
Check whether the input pulse edge (rise/fall) being counted is correct.
Check whether the maximum speed of the input pulse is within the range of the
counting speed set with "Input filter setting" of the module parameter.
Check whether the input pulse waveform meets the performance specifications.
Check whether 'CH1 Accumulating count value' (Un\G2, Un\G3) and 'CH1 Input
pulse value' (Un\G4, Un\G5) are read in units of two words (32 bits) when read
by a program.
Check whether the input pulse values are the same when the same pulse is
applied to multiple channels.
Check whether 'CH1 Count enable' (Y18) is on.
Check whether Overflow detection (1) is stored in 'CH1 Overflow detection flag'
(Un\G6).
Check whether 'CH1 Pre-scale setting value' (Un\G135) is set to 0.
3 TROUBLESHOOTING
50
3.3 Troubleshooting by Symptom
Action
Check the external wiring. ( MELSEC iQ-R Channel Isolated Pulse Input
Module User's Manual (Startup))
Use a shielded twisted pair cable for the pulse input cable.
Disconnect the ground cable of the pulse input module.
If the pulse input module case is in contact with the grounding part,
separate the pulse input module from the grounding part.
Implement measures to reduce noise such as attaching CR surge
suppressors to magnet switches and similar devices.
Ensure that the pulse input cable has its own pipe and, even with in-panel
wiring, keep a distance of 150mm or more between the pulse input cable
and the power cable.
If it turns on, check the external wiring and the wiring on the pulse generator
side.
If it remains off, the possible cause is a failure of the module. Please consult
your local Mitsubishi representative.
Correct "Input voltage selection" of the module parameter to match the
actual input pulse voltage.
Check whether the input pulses are being counted on the rising edge or on
the falling edge, and then correct "Pulse edge selection" of the module
parameter.
Correct "Input filter setting" of the module parameter to match the maximum
speed of the input pulse.
Observe and check the pulse waveform with a synchroscope or a similar
device. If the input pulse does not meet the performance specifications,
apply an input pulse that does. ( MELSEC iQ-R Channel Isolated Pulse
Input Module User's Manual (Startup))
Perform batch reading of these values in units of two words (32 bits).
If the input pulse values are different, the possible cause is a failure of the
module. Please consult your local Mitsubishi representative.
Turn on 'CH1 Count enable' (Y18) from a program.
Set 'CH1 Counter reset request' (Un\G386) to Reset request (1) to reset
'CH1 Accumulating count value' (Un\G2, Un\G3).
Set 'CH1 Pre-scale setting value' (Un\G135) to a value other than 0.